Memory devices including three-dimensionally arranged memory cells have been developed. For example, a NAND-type memory device has a structure in which electrode layers are stacked one on the other, and a memory cell is formed in the device where a memory hole penetrates each electrode layer. To increase the storage capacity of such a memory device, it is generally preferable to increase the number of stacked electrode layers. However, as the number of stacked electrode layers increases, it becomes more difficult to form memory holes that penetrate through each electrode layer in the stack.